The present invention relates to a beneficiation method, and particularly to such apparatus and methods in which the difference in the specific gravity of gangue and concentrate is utilized to achieve separation of severed ore.
Run-of-the-mine ore is usually too great in bulk and weight to permit shipping without initial processing at the mine to concentrate sought-after metals into a product of smaller bulk. The first step in conventional mine site processing is severance, in which the ore is comminuted by crushing, usually in several phases. The next step is beneficiation in which the severed ore is separated into concentrate, in which the metal is found, and gangue (also known as tailing), which is a waste product. The concentrate is then shipped to a refinery where pure metal is liberated by chemical or thermal means.
The profitability of a mine is often dependent upon the cost of beneficiation, and many mines that would yield low grade ore are not worked because of the high expense that this process would entail if known techniques were employed. Copper and precious metals, for instance, are often present in such low grade ore.
A common method of beneficiation used to recover such metals is called tabling. The severed ore is introduced onto a reciprocating deck which is continuously washed by a water film, the reciprocation of the deck being at right angles to the water flow. As the ore moves across the deck, the gangue and concentrate are stratified owing to the difference in their specific gravities, and the concentrate is trapped by riffles of successively increasing length raised on the surface of the deck.
Another known method of beneficiation applicable to severed metal ore is called sink-float separation. The ore is introduced into a suspension having a specific gravity higher than the gangue but lower than the metal. The suspension is stirred in a rotary fashion as it flows through a conically shaped vessel. The gangue tends to float across the top of the vessel and out the opposite side, while the concentrate sinks and is discharged through the pointed lower end of the vessel. In this, as in other beneficiation processes, the metal is not recovered in pure form nor is the gangue completely free of metal. The metal is, however, present in the concentrate in a much higher proportion than in the beneficiated ore, and the proportion of metal found in the gangue should be very small.
Known beneficiation techniques are often time-consuming, labor intensive and costly. The principle objective of the present invention is to provide a new and different beneficiation apparatus and method capable of processing severed ore within a short period of time, using less labor, and at a greatly reduced cost.